3h-naphth0 [2,1-b] pyrans as photochromic dichroic dyes and optical article containing them

ABSTRACT

A naphthopyran compound represented by the formula (I): 
     
       
         
         
             
             
         
       
     
     wherein:
         n 1 , n 2 , p, q is an integer comprised from 0 to 5 inclusive; m is an integer comprised from 0 to 4 inclusive;   R 1  and R 2  represent a group selected from halogen, —R a , —OH, —OR a , —SH, —SR a , —NH 2 , —NR a R a1 , —NR b R c , —CO—R a , and —CO 2 R a1 , wherein R a , R a1 , R b  and R c , are as defined in the description;   R 3  represents a group selected from halogen, —R a , —OH, —OR a , —SH, —SR a , —NH 2 , and —NR a R a1 ;   R 4  represents a group selected from halogen, —R a , —OH, —OR a , —SH, —SR a , —NH 2 , —NR a R a1 , —CO—R a , and —CO 2 R a1 ;   R 5  represents a group selected from:
           halogen, —R a , —OH, —OR a , —SH, —SR a , —NH 2 , and —NR a R a1 , wherein R a  and R a1  are as defined hereinbefore,   or when q is equal to 2, then two R 5  together represent further a group —O—(CH 2 ) q1 —O— wherein q1 represents an integer comprised from 1 to 3 inclusive.

TECHNICAL FIELD

The present invention is directed to a group of novel dyes that are bothphotochromic and dichroic and to the use thereof in optical articles,especially in optical lenses such as ophthalmic lenses.

BACKGROUND ART

Photochromism is a well known physical phenomenon that is observed withcertain classes of chemical compounds. A detailed discussion of thisphenomenon can be found in “Photochromism: Molecules and Systems”,Studies in Organic Chemistry 40, edited by H. Durr and H. Bouas-Laurent,Elsevier, 1990.

A number of substituted 3H-naphtho[2,1-b]pyrans are known to be capableof exerting a reversible photochromic effect as described for example inWO 99/31082, U.S. Pat. No. 6,630,597, U.S. Pat. No. 5,552,090, U.S. Pat.No. 5,520,853, and U.S. Pat. No. 5,623,005. However, none of these3H-naphtho[2,1-b]pyrans compounds are reported to have dichroicproperties.

Passive photochromic devices, i.e. devices containing photochromic dyeswhose absorbance depends only from the presence or absence of UV light,typically exhibit rather quick activation (coloration) but it generallytakes several minutes or even tens of minutes to revert from thecoloured to the bleached state. This slow fading is a severe drawbackfor the user of photochromic glasses who has to take them off to haveclear vision when leaving the sunlight and entering dimmer lightconditions.

Therefore, there is a need for photochromic dyes exhibiting not onlygood photochromic properties, such as high absorption in the colouredstate, fast colouring and fading rates, but which also may be capable ofdichroism and linear light polarization when in a spatially orderedcondition, for example when incorporated into liquid crystals ororiented polymer host materials.

SUMMARY OF THE INVENTION

In light of the foregoing, it is first aspect of the present inventionto provide a dye that is both photochromic and dichroic.

It is another aspect of the present invention to provide a naphthopyrancompound represented by the formula (I)

wherein:

-   -   n₁ is an integer comprised from 0 to 5 inclusive;    -   n₂ is an integer comprised from 0 to 5 inclusive;    -   p is an integer comprised from 0 to 5 inclusive;    -   m is an integer comprised from 0 to 4 inclusive;    -   q is an integer comprised from 0 to 5 inclusive;    -   R₁ and R₂, identical or different, independently from each        other, represent a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, —NR_(a)R_(a1), —NR_(b)R_(c),

—CO—R_(a), —O—CO—R^(a) and —CO₂R_(a1), wherein:

-   -   R_(a) represents a linear or branched (C₁-C₁₈) alkyl group or a        linear or branched (C₁-C₁₈) perfluoroalkyl group;    -   R_(a1) represents a group selected from hydrogen, linear or        branched (C₁-C₁₈) alkyl group and linear or branched (C₁-C₁₈)        perfluoroalkyl group;    -   R_(b) and R_(c),        -   together and in combination with the nitrogen atom,            represent a saturated 5 to 7 membered heterocyclic group            which comprises optionally one additional heteroatom            selected from O, N and S, and which may be optionally            substituted by a group selected from halogen, R_(a), —OH,            —OR_(a), —NH₂, and —NR_(a)R_(a1), wherein R_(a) and R_(a1)            are as defined hereinbefore;        -   or together and in combination with the nitrogen atom and            the adjacent phenyl group form a heterocyclic group of            formula (A):

-   -   R₃ represents a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, and —NR_(a)R_(a1), wherein R_(a)        and R_(a1) are as defined hereinbefore;    -   R₄ represents a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, —NR_(a)R_(a1), —CO—R_(a), and        —CO₂R_(a1), wherein R_(a) and R_(a1) are as defined        hereinbefore;    -   R₅ represents a group selected from:        -   halogen, —R_(a), —OH, —OR_(a), —SH, —SR_(a), —NH₂, and            —NR_(a)R_(a1), wherein R_(a) and R_(a1) are as defined            hereinbefore,        -   or when q is equal to 2 and then two R₅ substituents are            located onto two adjacent carbon atoms selected from C-7,            C-8, C-9 and C-10 of the naphtho[2,1-b]pyran group, they may            further represent together a group —O—(CH₂)_(q1)—O— wherein            q1 represents an integer comprised from 1 to 3 inclusive.

Yet another aspect of the present invention provides an optical articlecomprising one or more naphthopyran compounds of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides photochromic-dichroic3H-naphtho[2,1-b]pyrans having a substituted biphenyl group at C-6 ofthe naphthopyran group.

In one or more embodiments, incorporation of a biphenyl moietysignificantly improves dichroic properties of the photochromic dyes inthe activated state. The new dye compounds when incorporated intoanisotropic host materials such as liquid crystals or oriented polymerswill strongly align with the host material molecules and exhibit strongdichroism, i.e. light polarizing, in the coloured state. The new dyespresent an order parameter of greater than about 0.6 and excellentsolubility in liquid crystal hosts and most of organic solvents.

In certain embodiments, the photochromic dyes of the present inventionsurprisingly present a very fast fading rate, especially when dissolvedin a fluid, mesomorphous or gel host medium. In one or more embodiments,they are able to revert from the coloured to the bleached state in lessthan five minutes, which constitutes an important advantage over most ofthe prior art photochromic dyes.

Accordingly, the present invention provides naphthopyran compoundsrepresented by the formula (I)

wherein:

-   -   n₁ is an integer comprised from 0 to 5 inclusive;    -   n₂ is an integer comprised from 0 to 5 inclusive;    -   p is an integer comprised from 0 to 5 inclusive;    -   m is an integer comprised from 0 to 4 inclusive;    -   q is an integer comprised from 0 to 5 inclusive;    -   R₁ and R₂, identical or different, independently from each        other, represent a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, —NR_(a)R_(a1), —NR_(b)R_(c),

—CO—R_(a), —O—CO—R^(a) and —CO₂R_(a1), wherein:

-   -   R_(a) represents a linear or branched (C₁-C₁₈) alkyl group or a        linear or branched (C₁-C₁₈) perfluoroalkyl group;    -   R_(a1) represents a group selected from hydrogen, linear or        branched (C₁-C₁₈) alkyl group and linear or branched (C₁-C₁₈)        perfluoroalkyl group;    -   R_(b) and R_(c),        -   together and in combination with the nitrogen atom,            represent a saturated 5 to 7 membered heterocyclic group            which comprises optionally one additional heteroatom            selected from O, N and S, and which may be optionally            substituted by a group selected from halogen, R_(a), —OH,            —OR_(a), —NH₂, and —NR_(a)R_(a1), wherein R_(a) and R_(a1)            are as defined hereinbefore;        -   or together and in combination with the nitrogen atom and            the adjacent phenyl group form a heterocyclic group of            formula (A):

-   -   R₃ represents a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, and —NR_(a)R_(a1), wherein R_(a)        and R_(a1) are as defined hereinbefore;    -   R₄ represents a group selected from halogen, —R_(a), —OH,        —OR_(a), —SH, —SR_(a), —NH₂, —NR_(a)R_(a1), —CO—R_(a), and        —CO₂R_(a1), wherein R_(a) and R_(a1) are as defined        hereinbefore;    -   R₅ represents a group selected from:        -   halogen, —R_(a), —OH, —OR_(a), —SH, —SR_(a), —NH₂, and            —NR_(a)R_(a1), wherein R_(a) and R_(a1) are as defined            hereinbefore,        -   or when q is equal to 2 and then two R₅ substituents are            located onto two adjacent carbon atoms selected from C-7,            C-8, C-9 and C-10 of the naphtho[2,1-b]pyran group, they may            further represent together a group —O—(CH₂)_(q1)—O— wherein            q1 represents an integer comprised from 1 to 3 inclusive.

Preferred naphthopyrans according to the present invention are compoundsof formula (I), wherein:

-   -   n₁ is equal to 0 or 1, and R₁ represents a group selected from        halogen, —OH and —OR_(a) located at the para- or ortho-position        of the phenyl group, wherein R_(a) is as defined hereinbefore;    -   n₂ is equal to 1 and R₂ represents a group selected from        halogen, —OH, —OR_(a), and —NR_(b)R_(c) located at the        para-position of the phenyl group, wherein R_(a), R_(b) and        R_(c) are as defined hereinbefore;    -   m is equal to zero;    -   p is equal to 1 and R₄ represents a group selected from —R_(a),        —OR_(a), and —NR_(a)R_(a1) located at the para-position of the        phenyl group; and    -   q is an integer comprised from 0 to 2 inclusive, and R₅        represents a group selected from —OH and —OR_(a) located on the        C-8 and/or C-9 of the naphtho[2,1-b]-pyran group.

Examples of most preferred compounds of formula (I) are the compoundsrepresented by the following formulas (a) to (p):

Compounds represented by formula (I) may be prepared according to thefollowing descriptions and reaction schemes: The requisite naphthols maybe prepared as shown in Schemes 1-4. For example, 4-bromo-2-naphthol 1may be prepared, as shown in Scheme 1, by sequential bromination,diazotisation and reduction of 1-naphthylamine according to thepublished procedure (M. S. Newman, V. Sankaran and D. Olson, J. Am.Chem. Soc., 1976, 98, 3237), which is hereby incorporated by reference.

1,3-Dihydroxynapthalene is readily available according to the procedureof Meyer and Bloch; (Org. Synth. Coll. Vol., 3, p. 637), herebyincorporated by reference, and may be selectively methylated to give3-methoxy-1-naphthol in high yield as described in K. H. Bell and L. F.McCaffrey, Aust. J. Chem., 1993, 46, 731, which is hereby incorporatedby reference. Subsequent sulfonylation with trifluoromethanesulfonicanhydride provides the trifate 2 in about a 74% yield (Scheme 2), andthis procedure is described in S. C. Benson, J. Y. L. Lam, S. M.Menchen, U.S. Pat. No. 5,936,087, hereby incorporated by reference.

Suzuki-Miyaura coupling of 2 with 4′-methoxybiphenyl-4-boronic acid maybe employed to give 3, after treatment with excess boron tribromide(Scheme 3). Suzuki-Miyaura coupling is described in A. Suzuki, J.Organomet. Chem., 1999, 576, 147; N. Miyaura, Top. Curr. Chem., 2002,219, 11, hereby incorporated by reference. 4′-methoxybiphenyl-4-boronicacid is further described in V. Percec, P. Chu and M. Kawasumi,Macromolecules, 1994, 27, 4441, hereby incorporated by reference.

The preparation of naphthol 4 may involve an initial Claisen-typecondensation of methyl (3,4-dimethoxyphenyl)acetate and4′-bromoacetophenone mediated by sodium hydride (Scheme 4). Acylationreactions of this type of active CH compound have been reviewed (C. R.Hauser, F. W. Swamer and J. T. Adams, Org. React., 1954, 8, 126; B. R.Davies and P. J. Garratt, Comprehensive Organic Synthesis, Pergamon,Oxford, 1991, vol. 2, p. 795, both of which are incorporated byreference). Cyclodehydration of the intermediate 1,3-diketone to 4 maybe accomplished under acidic conditions (A. V. Kel'in and Y. Yu.Kozyrkov Synthesis, 1998, 729; WO 99/31082, both of which areincorporated by reference).

The preparation of 1,1-diarylprop-2-yn-1-ols 5 from lithiumtrimethylsilylacetylide and a benzophenone according to Scheme 5 hasbeen documented (e.g. C. D. Gabbutt, J. D. Hepworth, B. M. Heron, S. M.Partington and D. A. Thomas, Dyes Pigm., 2001, 49, 65, which isincorporated by reference).

The preparation of the 6-substituted naphtho[2,1-b]pyrans may beaccomplished by the acid catalysed condensation of the appropriate2-naphthol 1, 3 or 4 and alkynol derivatives 5 as shown in Scheme 6.This route to naphthopyrans has been reviewed (B. Van Gemert, OrganicPhotochromic and Thermochromic Compounds Volume 1: Main PhotochromicFamilies, Ed. J. C. Crano and R. Gugglielmetti, Plenum Press, New York,1998, p. 111; J. D. Hepworth and B. M. Heron, Functional Dyes, Ed. S.-H.Kim, Elsevier, Amsterdam, 2006, p. 85; C. D. Gabbutt, B. M. Heron, A. C.Instone, P. R. Horton, M. B. Hursthouse, Tetrahedron, 2005, 61, p. 463,all of which are hereby incorporated by reference).

The bromonaphthopyrans 6 and 8 may serve as substrates for furthermodification by Suzuki-Miyaura coupling to the appropriate4′-substituted-4-biphenylboronic acid (prepared as described by e.g. M.R. Friedman, K. J. Toyne, J. W. Goodby and M. Hird, Liquid Crystals,2001, 28, 901, hereby incorporated by reference) and 4-substitutedphenylboronic acid to give the6-(4′-substituted-4-biphenyl)naphtho[2,1-b]pyrans of general structure(I) as illustrated by examples (a)-(j) and (m)-(p) respectively.Alternatively, the naphthopyran 7 may be alkylated as illustrated byexamples (k) and (l). These three general sequences are shown in Scheme7. More specifically, the preparation of Example (1) is outlined inScheme 8. Noteworthy is the assembly of the 6-(4′-hydroxy-4-biphenyl)moiety via Suzuki-Miyaura coupling of a bromonaphthopyran derivative 8to readily available 4-(triisopropylsilyloxy)phenylboronic acid (D. J.Aitken, S. Faure and S. S. Roche, Tetrahedron Lett., 2003, 44, 8827, seealso M. E. Hart et al. J. Med. Chem., 2006, 49, 1101, both of which arehereby incorporated by reference).

The present invention also provides an optical article comprising one ormore naphthopyran compounds (I) of the present invention. Thenaphthopyran compounds (I) of the present invention can be used in allkinds of optical devices and elements, such as ophthalmic elements anddevices, display elements and devices, windows or mirrors. Non-limitingexamples of ophthalmic elements include corrective and non-correctivelenses, including single vision or multi-vision lenses, which may beeither segmented or non-segmented, as well as other elements used tocorrect, protect, or enhance vision, including without limitationcontact lenses, intra-ocular lenses, magnifying lenses and protectivelenses or visors. Non-limiting examples of display elements and devicesinclude screens and monitors. Non-limiting examples of windows includeautomotive and aircraft transparencies, filters, shutters, and opticalswitches.

The optical article of the present invention is preferably a lens, andmore preferably an ophthalmic lens.

When used in optical articles, the naphthopyran compounds may beincorporated, for example, in the bulk of a polymeric material of theoptical article. Such a polymeric host material is generally a solidtransparent or optically clear material. Preferred polymeric hostmaterials are for example polymers of polyol(allyl carbonate) monomers,polyacrylates, poly(triethyleneglycol dimethacrylate),polyperfluoroacrylates, cellulose acetate, cellulose triacetate,cellulose acetate propionate, cellulose acetate butyrate, poly(vinylacetate), poly(vinyl alcohol), polyurethanes, polycarbonates,poly(ethylene terephthalate), polystyrene, polyfluorostyrene,poly(diethylene glycol bis(alkyl carbonate)) and mixtures thereof.

The photochromic substances of the present invention may be incorporatedinto the polymeric host material by various methods described in theart. Such methods include dissolving or dispersing the photochromicsubstance within the host material by adding it to the monomeric hostmaterial prior to polymerization, or by imbibition of the photochromicsubstance into the host material by immersion of the host material in ahot solution of the photochromic substance.

In another preferred embodiment of the present invention thephotochromic dyes are not incorporated into the bulk of an organicpolymeric host material, but are incorporated into a surface coating ora film applied onto an optical substrate. The substrate is preferably atransparent or optically clear material, such as glass or organicpolymers commonly used in optical applications.

The present invention of course also encompasses optical articles havingat least one naphthopyran compound of formula (I) incorporated either inthe bulk of the article, or in the coating of the article, or in thefilm applied onto the article. In one or more embodiments, the opticalarticle includes a naphthopyran compound of formula (I) incorporatedboth into the bulk and into the coating of the article.

In still a more preferred embodiment of the present invention, thecoating or film incorporating the photochromic naphthopyran compounds ofthe present invention is an anisotropic film or coating, i.e. itcomprises a layer or medium which is able to function as an alignmentlayer for the dye molecules. Such an alignment layer may be for examplean organic polymer, such as polyvinyl alcohol (PVA). One common methodof aligning the molecules of a dichroic dye involves heating a sheet orlayer of PVA to soften the PVA and then stretching the sheet to orientthe polymer chains. The dichroic dye is then impregnated into thestretched sheet and dye molecules take the orientation of the polymerchains. Alternatively, the dichroic dye can be first impregnated intothe PVA sheet, and thereafter the sheet can be heated and stretched asdescribed above to orient the PVA polymer chains and associated dyes. Inthis manner, the molecules of the dichroic dye can be suitablypositioned or arranged within the oriented polymer chains of the PVAsheet and a net linear polarization can be achieved.

In an even more preferred embodiment of the present invention, the novelnaphthopyran compounds are not incorporated into a solid, isotropic oranisotropic host material, but into a fluid, mesomorphous or gel hostmedium. Dissolving or dispersing the naphthopyran compounds of thepresent invention in such a fluid, mesomorphous or gel host mediumincreases the coloration rate and even more drastically the fading rate.The recovery time, i.e. the time it takes the material to revert from anabsorptive condition to a clear condition, can thus be reduced to lessthan 5 minutes.

The fluid or mesomorphous host medium incorporating at least onenaphthopyran compound is preferably selected from the group consistingof organic solvents, liquid crystals, and mixtures thereof.

The naphthopyran compounds of the present invention are preferablydissolved in the host medium.

The organic solvents may be selected for example from the groupconsisting of benzene, toluene, methyl ethyl ketone, acetone, ethanol,tetrahydrofurfuryl alcohol, N-methylpyrrolidone, 2-methoxyethyl ether,xylene, cyclohexane, 3-methylcyclohexanone, ethyl acetate, ethylphenylacetate, tetrahydrofuran, methanol, methyl propionate, ethyleneglycol and mixtures thereof.

The liquid crystal medium that may be used in the present inventionincludes, without being limited to, such materials as nematic or chiralnematic media. Alternatively a polymeric liquid crystal medium can beused as the host material. These liquid crystal and polymeric liquidcrystal media are generally used in combination with an organic solvent,for example one of the organic solvents mentioned above.

The mixture of a fluid, mesomorphous or gel host medium and at least oneof the naphthopyran compounds of the present invention preferably isincorporated into a device containing a mechanism for holding themixture in a mechanically stable environment.

Such a device is disclosed for example in U.S. Pat. No. 6,690,495 whichis hereby specifically incorporated by reference herein. Such a devicecomprises a pair of opposed substrates having a gap therebetween forreceiving the mixture of a fluid, mesomorphous or gel host medium and atleast one photochromic dye of the present invention, and a frame forholding said pair of substrates adjacent one another.

An even more preferred device for holding the mixture in a mechanicallystable environment is the one described in WO 2006/013250 and FR2879757, which are hereby specifically incorporated by reference herein.

The preferred optical article of the present invention, disclosed in WO2006/013250, comprises an optical component provided with at least onetransparent cell arrangement juxtaposed in a parallel direction to thesurface thereof, each cell being tightly closed and containing saidfluid, mesomorphous or gel host medium and said at least onenaphthopyran compound of the present invention. The transparent cellarrangement forms a layer whose height perpendicular to the componentsurface is less than 100 μm, preferably comprised between 1 μm and 50μm.

The transparent cell arrangement may be formed either directly on atransparent rigid substrate of said optical component, or alternativelya transparent film incorporating the transparent cell arrangement may beapplied on a transparent rigid substrate of the optical component.

The cell arrangement preferably occupies a large fraction of the totalsurface of the optical component. The ratio of the total surfaceoccupied by the cells to the total surface of the optical component ispreferably at least 90%, more preferable comprised between 90 and 99.5%,and most preferably between 96% and 98.5%.

The cell arrangement may be composed for example of hexagonal orrectangular cells, whose dimensions may be described by

-   -   (a) their size parallel to the surface of the optical component,        which is preferably of at least 1 μm, more preferably comprised        between 5 μm and 100 μm;    -   (b) the height of the cells perpendicular to the component        surface, which is preferably less than 100 μM, and is more        preferably comprised between 1 μm and 50 μm; and    -   (c) the thickness of the partitions separating the tightly        closed cells from each other, which is preferable comprised        between 0.10 and 5.00 μm.

EXAMPLES Synthesis of Intermediate Compounds Used in the Synthesis ofExample Compounds 3-Methoxynaphthalen-1-yl trifluoromethanesulfonate

Trifluoromethanesulfonic anhydride (9.35 g, 32.8 mmol) was addeddropwise to a solution of 3-methoxy-1-naphthol (5.77 g, 32.8 mmol) andEt₃N (10 ml) in dichloromethane (100 ml) at 0° C. with stirring. After 1h the resulting solution was washed with HCl (50 ml, 1 M) and saturatedNa₂CO₃ (50 ml), dried (MgSO₄) and the solvent removed under reducedpressure. The residue was chromatographed on silica using EtOAc (7% inhexanes) to give the title compound (7.45 g, 74%) as a colourless oil.

3-Methoxy-1-(4′-methoxy-4-biphenyl)naphthalene

A mixture of 3-methoxynaphthalen-1-yl trifluoromethanesulfonate (0.5 g,1.7 mmol), (4′-methoxy-4-biphenyl)boronic acid (0.58 g, 2.5 mmol),Na₂CO₃ (0.27 g, 2.5 mmol) and Pd(PPh₃)₄ (40 mg, 2 mol %) in PhMe (20 ml)and EtOH (20 ml) under N₂ was heated at reflux. After 2 h the mixturewas cooled, poured into water (100 ml), extracted with dichloromethane(3×50 ml), dried (MgSO₄) and the solvent removed under reduced pressure.The residue was dissolved in dichloromethane, filtered through a shortplug of silica and the solvent removed under reduced pressure to givethe title compound (0.44 g, 76%) as a colourless powder.

4-(4′-Hydroxy-4-biphenyl)-2-naphthol

Boron tribromide (1.00 g, 3.9 mmol) was added dropwise to a solution of3-methoxy-1-(4′-methoxy-4-biphenyl)naphthalene (0.44 g, 1.3 mmol) indichloromethane (50 ml) at 0° C. under N₂. The solution was warmed to rtand stirring continued overnight, poured into water (200 ml), extractedwith Et₂O (3×50 ml), dried (MgSO₄) and the solvent removed under reducedpressure to give the title compound (0.40 g, 100%) as a brown powder.

1-(4-Bromophenyl)-4-(3,4-dimethoxyphenyl)butane-1,3-dione

Sodium hydride (60% dispersion, 3.80 g, 95.1 mmol) was added portionwiseto methyl 2-(3,4-dimethoxyphenyl)acetate (10 g, 47.6 mmol) in Et₂O (100ml) at 0° C. A solution of 4′-bromoacetophenone (9.48 g, 47.6 mmol) inEt₂O (50 ml) was added dropwise over 1 h. The mixture was heated atreflux for 16 h, cooled, poured into ice/HCl (2 M), extracted with Et₂O(3×100 ml), dried (MgSO₄) and the solvent removed under reducedpressure. The residue was crystallized from MeOH to give the titlecompound (9 g, 50%) as a tan powder.

4-(4-Bromophenyl)-6,7-dimethoxy-2-naphthol

1-(4-Bromophenyl)-4-(3,4-dimethoxyphenyl)butane-1,3-dione (3 g, 8 mmol)in 85% phosphoric acid was heated at 70° C. for 20 h. The resultingsolution was cooled, poured into water (150 ml) and filtered. Theresidue was dissolved in dichloromethane (50 ml), washed with water (50ml), dried (MgSO₄) and the solvent was removed under reduced pressure togive the title compound (2.56 g, 90%) as a brown powder.

General Procedure for the Synthesis of6-bromophenyl-8,9-dimethoxynaphtho[2,1-b]pyrans

A mixture of 4-(4-bromophenyl)-6,7-dimethoxy-2-naphthol (9.7 mmol),1,1-diarylprop-2-yn-1-ol (9.7 mmol) and acidic alumina (3 g) in toluene(100 ml) was heated at reflux. After 2 h the solution was filtered hotand the residue was washed with PhMe (50 ml). The solvent was removedunder reduced pressure and the residue chromatographed on silica. Thesolvent was removed under reduced pressure and the residue was washedwith MeOH to give the title compound which was purified by flashchromatography from silica gel. The following compounds were prepared inthis way:

6-(4-Bromophenyl)-8,9-dimethoxy-3-phenyl-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyrandichloromethane (70% in hexanes) as eluent, 69% as a purple powder

6-(4-Bromophenyl)-8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphol[2,1-b]pyrandichloromethane as eluent, 64% as a violet powder

6-(4-Bromophenyl)-8,9-dimethoxy-3-(4-butoxyphenyl)-3-(9-julolidinyl)-3H-naphtho[2,1-b]pyrandichloromethane as eluent, 51% as a green powder

General Procedure for the Synthesis of 6-biphenylnaphtho[2,1-b]pyransfrom 6-bromonaphthopyrans

The appropriate 6-bromo-3H-naphtho[2,1-b]pyran (1 mmol) was dissolved inTHF (10 ml) containing water (1 ml) under nitrogen and[1,1′-bis(diphenylphosphino)ferrocene]dichloro palladium(II) (1 mol %)was added. The solution was stirred for 5 min and potassium carbonate(1.1 mmol), potassium fluoride (3.3 mmol) and the appropriate4′-substituted-4-biphenylboronic acid (1.1 mmol) were added. Thereaction mixture was refluxed for 20 hours. Solvent was removed and theresidue was flash chromatographed using petroleum ether-ethyl acetate(97-3) on silica gel. Recrystallisation from ethyl acetate and hexanegave the title compounds.

The following examples were prepared using the intermediate stepsdescribed hereinbefore in this way.

Example (a)

6-(4′-Pentyl-4-biphenyl)-3-phenyl-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyran(m.p. 95-97° C.) from6-bromo-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyran and4′-pentylbiphenyl-4-boronic acid.

Example (b)

6-(4′-Pentyl-4-biphenyl)-3-(4-methoxyphenyl)-3-(4-morpholinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 166-167° C.) from6-bromo-3-(4-methoxyphenyl)-3-(4-morpholinophenyl)-3H-naphtho[2,1-b]pyranand 4′-pentylbiphenyl-4-boronic acid.

Example (c)

6-(4′-Pentyl-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 155-157° C.) from6-bromo-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran and4′-pentylbiphenyl-4-boronic acid.

Example (d)

6-(4′-Pentyl-4-biphenyl)-3-phenyl-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyran:(m.p. 130-132° C.) from6-bromo-3-phenyl-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyran and4′-pentylbiphenyl-4-boronic acid.

Example (e)

6-(4′-Pentyl-4-biphenyl)-3-(4-methoxyphenyl)-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyran:(m.p. 89° C.) from6-bromo-3-(4-methoxyphenyl)-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyranand 4′-pentylbiphenyl-4-boronic acid.

Example (f)

6-(4′-Pentyl-4-biphenyl)-3-phenyl-3-(4-fluorophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 55° C.) from6-bromo-3-phenyl-3-(4-fluorophenyl)-3H-naphtho[2,1-b]pyran and4′-pentylbiphenyl-4-boronic acid.

Example (g)

6-(4′-Butoxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 107° C.) from6-bromo-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran and4′-butoxybiphenyl-4-boronic acid.

Example (h)

6-(4′-Hexyloxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 93° C.) from6-bromo-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran and4′-hexyloxybiphenyl-4-boronic acid.

Example (i)

6-(4′-Hexyloxy-4-biphenyl)-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 149° C.) from6-bromo-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyranand 4′-hexyloxybiphenyl-4-boronic acid.

Example (j)

6-(4′-Pentyl-4-biphenyl)-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran:(m.p. 153° C.) from6-bromo-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyranand 4′-pentylbiphenyl-4-boronic acid.

General Procedure for the Synthesis of6-biphenyl-8,9-dimethoxynaphtho[2,1-b]pyrans front6-bromophenyl-8,9-dimethoxynaphthopyrans

A mixture of the appropriate 6-bromophenyl-8,9-dimethoxynaphthopyran(2.4 mmol), and an arylboronic acid (3.6 mmol) in 1,2-dimethoxyethane(50 ml) was degassed by purging with nitrogen.Tetrakis(triphenylphosphine)palladium(0) (5 mol %) was added followed byNa₂CO₃ (7.2 mmol) in degassed water (50 ml). The mixture was heated at100° C. for 16 h, cooled, poured into water, extracted withdichloromethane (5×50 ml), dried (MgSO₄) and the solvent removed underreduced pressure. The residue was chromatographed on silica. The solventwas removed under reduced pressure and the residue crystallised fromacetone-methanol by slow evaporation to give the title compounds.

The following examples were prepared using the intermediate stepsdescribed hereinbefore in this way.

Example (m)

6-(4′-Hexyloxy-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyran dichloromethane as eluent, 72% as apurple powder, mp 198-199° C.

Example (n)

6-(4′-Dibutylamino-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyranbutanone (15% in cyclohexane) as eluent, 73% as a colourless powder, mp174-175° C.

Example (o)

6-(4-(Hexyloxy-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyranbutanone (20% in cyclohexane) as eluent, 76% as a colourless powder, mp197-198° C.

Example (p)

3-(4-Butoxyphenyl)-8,9-dimethoxy-6-(4′-hexyloxy-4-biphenyl)-3-(9-julolidinyl)-3H-naphtho[2,1-b]pyranacetone, butanone, cyclohexane (8:8:84) as eluent, 53% as a violetpowder, mp 111-112° C.

8,9-Dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-6-(4′-triisopropylsilyloxy-4-biphenyl)]-3H-naphtho[2,1-b]pyrandichloromethane as eluent, 70% as a colourless powder

8,9-Dimethoxy-6-(4′-(hydroxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran

A solution of tetrabutylanimonium fluoride (1M in THF) (1.26 mmol) wasadded to a solution of8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-6-(4′-triisopropylsilyloxy-4-biphenyl)-3H-naphtho[2,1-b]pyran(1.26 mmol) in THF (30 ml) with stirring. After 5 min HCl (3 ml, 1 M)was added and the solvent removed under reduced pressure. The residuewas chromatographed on silica using dichloromethane (70% in hexanes) aseluent The solvent was removed under reduced pressure and the residuecrystallised from acetone/MeOH to give the title compound (57%) as acream powder, mp 154-155° C.

Example (l)8,9-Dimethoxy-6-(4′-dodecyloxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran

To a solution of8,9-dimethoxy-6-(4′-hydroxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran(0.63 g, 1.0 mmol) and 1-iododecane (0.59 g, 2.0 mmol) in acetone (50ml) was added potassium carbonate (1.38 g, 10 mmol) and the mixturerefluxed for 6 h. After this time the mixture was poured into water andextracted with dichloromethane (3×50 ml). The extracts were dried andevaporated and the residue triturated with acetone to provide the titlecompound (70%) as a colourless powder, mp 173-175° C.

Example (k)6-(4′-Dodecyloxy-4-biphenyl)-3-(4-hexyloxyphenyl)-3-[4-(4-methylpiperidino)phenyl]-3H-naphtho[2,1-b]pyran

To a solution of6-(4′-hydroxy-4-biphenyl)-3-[4-(hexyloxy)phenyl]-3-[4-(4-methylpiperidino)phenyl]-3H-naphtho[2,1-b]pyran(0.73 g, 1.0 mmol) and 1-iododecane (0.59 g, 2.0 mmol) in acetone (50ml) was added potassium carbonate (0.72 g, 5 mmol) and the mixturerefluxed for 24 h. After this time the mixture was poured into water andextracted with dichloromethane (3×50 ml). The extracts were dried andevaporated and the residue filtered through a short plug of silica using60% dichloromethane in hexanes as eluent. The solvent was removed andthe residue crystallised from acetone-methanol to give the titlecompound (0.81 g, 89%) as a pink powder, mp 45° C.

1. A naphthopyran compound represented by the formula (I):

wherein: n₁ is an integer comprised from 0 to 5 inclusive; n₂ is aninteger comprised from 0 to 5 inclusive; p is an integer comprised from0 to 5 inclusive; m is an integer comprised from 0 to 4 inclusive; q isan integer comprised from 0 to 5 inclusive; R₁ and R₂, identical ordifferent, independently from each other, represent a group selectedfrom halogen, —R_(a), —OH, —OR_(a), —SH, —NH₂, —NR_(a)R_(a1),—NR_(b)R_(c), —CO—R_(a), —O—CO—R^(a) and —CO₂R_(a1), wherein: R_(a)represents a linear or branched (C₁-C₁₈) alkyl group or a linear orbranched (C₁-C₁₈) perfluoroalkyl group; R_(a1) represents a groupselected from hydrogen, linear or branched (C₁-C₁₈) alkyl group andlinear or branched (C₁-C₁₈) perfluoroalkyl group; R_(b) and R_(c),together and in combination with the nitrogen atom, represent asaturated 5 to 7 membered heterocyclic group which comprises optionallyone additional heteroatom selected from O, N and S, and which may beoptionally substituted by a group selected from halogen, R_(a), —OH,—OR_(a), —NH₂, and —NR_(a)R_(a1), wherein R_(a) and R_(a1) are asdefined hereinbefore; or together and in combination with the nitrogenatom and the adjacent phenyl group form a heterocyclic group of formula(A):

R₃ represents a group selected from halogen, —R_(a), —OH, —OR_(a), —SH,—SR_(a), —NH₂, and NR_(a)R_(a1), wherein R_(a) and R_(a1) are as definedhereinbefore; R₄ represents a group selected from halogen, —R_(a), —OH,—OR_(a), —SH, —SR_(a), —NH₂, —NR_(a)R_(a1), —CO—R_(a), and —CO₂R_(a1),wherein R_(a) and R_(a1) are as defined hereinbefore; R₅ represents agroup selected from: halogen, —R_(a), —OH, —OR_(a), —SH, —SR_(a), —NH₂,and —NR_(a)R_(a1), wherein R_(a) and R_(a1) are as defined hereinbefore,or when q is equal to 2 and then two R₅ substituents are located ontotwo adjacent carbon atoms selected from C-7, C-8, C-9 and C-10 of thenaphtho[2,1-b]pyran group, they may further represent together a group—O—(CH₂)_(q1)—O— wherein q1 represents an integer comprised from 1 to 3inclusive.
 2. The naphthopyran compound according to claim 1, wherein:n₁ is equal to 0 or 1, and R₁ represents a group selected from halogen,—OH and —OR_(a) located at the para- or ortho-position of the phenylgroup, wherein R_(a) is as defined hereinbefore; n₂ is equal to 1 and R₂represents a group selected from halogen, —OH, —OR_(a), and —NR_(b)R_(c)located at the para-position of the phenyl group, wherein R_(a), R_(b)and R_(c) are as defined hereinbefore; m is equal to zero; p is equal to1 and R₄ represents a group selected from —R_(a), —OR_(a), and—NR_(a)R_(a1) located at the para-position of the phenyl group; and q isan integer comprised from 0 to 2 inclusive, and R₅ represents a groupselected from —OH and —OR_(a) located on the C-8 and/or C-9 of thenaphtho[2,1-b]-pyran group.
 3. The naphthopyran compound of claim 1,which is selected from one of the following compounds:6-(4-Pentyl-4-biphenyl)-3-phenyl-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-(4-methoxyphenyl)-3-(4-morpholinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-phenyl-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-(4-methoxyphenyl)1-3-(julolidin-9-yl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-phenyl-3-(4-fluorophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Butoxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Hexyloxy-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Hexyloxy-4-biphenyl)-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Pentyl-4-biphenyl)-3-(4-fluorophenyl)-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Hexyloxy-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-piperidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4′-(Dibutylamino)-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;6-(4-Hexyloxy-4-biphenyl)-8,9-dimethoxy-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;3-(4-Butoxyphenyl)-8,9-dimethoxy-6-(4′-hexyloxy-4-biphenyl)-3-(9-julolidinyl)-3H-naphtho[2,1-b]pyran;8,9-Dimethoxy-6-(4′-dodecyloxy)-4-biphenyl)-3-phenyl-3-(4-pyrrolidinophenyl)-3H-naphtho[2,1-b]pyran;and8,9-Dimethoxy-6-(4′-dodecyloxy-4-biphenyl)-3-(4-hexyloxyphenyl)-3-[4-(4-methylpiperidino)phenyl]-3H-naphtho[2,1-b]pyran.4. An optical article comprising at least one naphthopyran compoundaccording to claim
 1. 5. Optical article according to claim 4, whereinthe said article comprises further a polymeric host material, the atleast one naphthopyran compound being incorporated in the bulk of saidpolymeric host material.
 6. Optical article according to claim 5,wherein the polymeric host material is selected from polymers ofpolyol(allyl carbonate) monomers, polyacrylates, poly(triethyleneglycoldimethacrylate), polyperfluoroacrylates, cellulose acetate, cellulosetriacetate, cellulose acetate propionate, cellulose acetate butyrate,poly(vinyl acetate), poly(vinyl alcohol), polyurethanes, polycarbonates,poly(ethylene terephthalate), polystyrene), polyfluorostyrene,poly(diethylene glycol bis(alkyl carbonate)) and mixtures thereof. 7.Optical article according to claim 4, wherein the said article comprisesan optical substrate and at least one film or coating comprising the atleast one naphthopyran compound.
 8. Optical article according to claim7, wherein the at least one film or coating is a dichroic film orcoating comprising an anisotropic oriented polymer layer and the atleast one naphthopyran compound.
 9. Optical article according to claim4, wherein the article includes a fluid host medium, a mesomorphous hostmedium or a gel host medium, or a mixture of a fluid, mesomorphous orgel host medium, and at least one naphthopyran compound, wherein thenaphthopyran compound is dissolved or dispersed within the host medium.10. Optical article according to claim 9, wherein the fluid,mesomorphous or gel host medium incorporating the at least onenaphthopyran compound is selected from the group consisting of organicsolvents, liquid crystals, liquid crystal polymers and mixtures thereof.11. Optical article according to claim 9, wherein the said articlecomprises a device that includes a mechanism for holding the mixture ina mechanically stable environment.
 12. Optical article according toclaim 11, wherein the said device comprises a pair of opposed substrateshaving a gap there between for receiving the mixture of the host mediumand the at least one photochromic dye, and a frame for holding said pairof substrates adjacent one another.
 13. Optical article according toclaim 11, wherein the said device comprises an optical componentprovided with at least one transparent cell arrangement juxtaposed in aparallel direction to the surface thereof, each cell being tightlyclosed and containing said fluid host medium and said at least onenaphthopyran compound.
 14. Optical article according to claim 13,wherein the said transparent cell arrangement forms a layer whose heightperpendicular to the component surface is less than 100 μm.
 15. Opticalarticle according to claim 13, wherein the said optical componentcomprises a transparent rigid substrate whereon is formed thetransparent cell arrangement.
 16. Optical article according to claim 13,wherein the said optical component comprises a transparent rigidsubstrate and, applied on said substrate, a transparent filmincorporating the transparent cell arrangement.
 17. Optical articleaccording to claim 13, wherein the ratio of the total surface occupiedby the cells to the total surface of the optical component is at least90%.
 18. Optical article according to claim 13 wherein the cells have asize of at least 1 μm, parallel to the surface of the optical component.19. Optical article according to claim 13, wherein the cells areseparated from each other by means of partitions having a thickness of0.10 to 5.00 μm.
 20. Optical article according to claim 13, wherein thesaid article is selected from the group consisting of ophthalmicelements, ophthalmic devices, display elements display devices, windows,and mirrors, preferably lenses, and most preferably ophthalmic lenses.21. Optical article according to claim 14, wherein the said transparentcell arrangement forms a layer whose height perpendicular to thecomponent surface is comprised between 1 μm and 50 μm.
 22. Opticalarticle according to claim 17, wherein the ratio of the total surfaceoccupied by the cells to the total surface of the optical component iscomprised between 90 and 99.5%,
 23. Optical article according to claim22, wherein the ratio of the total surface occupied by the cells to thetotal surface of the optical component is comprised between 96% and98.5%.